Can I get a health certificate on May Day in Shenzhen?

You can't. Shenzhen will go to Shenzhen Center for Disease Control and Prevention to apply for a health certificate. As Shenzhen CDC enjoys legal holidays, May Day is a holiday, so Shenzhen May Day cannot apply for a health certificate. Shenzhen, referred to as Pengcheng for short, is a prefecture-level city under the jurisdiction of Guangdong Province.